Epidermal necrolysis (EN) compromises a spectrum of life-threatening dermatoses (Stevens-Johnson Syndrome [SJS], overlap syndrome and toxic epidermal necrolysis [TEN]). Currently, no active therapeutic regimen with unequivocal benefit exists for SJS/TEN. SCORTEN is the widely-used prognostic scale specific for SJS/TEN. Nevertheless, a new prognostic scale, the ABCD-10, has been recently proposed. In this context, acute renal failure (ARF) seems to be an important comorbidity that could influence prognosis in SJS/TEN patients more than it is assumed by these two scales. Our objectives were to compare the accuracy of the SCORTEN and ABCD-10 scales in predicting the mortality in SJS/TEN, and to investigate the influence of renal failure on prognosis. The prognostic results of 18 patients with EN treated in two referral centers between 2013 and 2018 are presented. SCORTEN, ABCD-10 and renal function values were retrospectively collected for all patients. Out of the 18 patients who were analyzed, nine (50%) received only supportive therapy, four were treated with etanercept 50 mg in a single dose (22.2%) and five with corticosteroids (27.8%). Five patients developed ARF. Predicted mortality was 3.48 for SCORTEN and 2.33 for ABCD-10. Eventually, four patients died (22.2%), all had ARF and none of them received active treatment. Despite study limitations and in the absence of active treatment of choice, SCORTEN behaved as a reliable predictor of mortality in patients with EN, outperforming the newer ABCD-10. ARF was an early event associated with a poor prognosis, which could represent a prognostic marker to consider in the future.